Piezoelectric resonator devices typified by piezoelectric resonators are widely used in mobile communication devices such as cellular phones and the like. A tuning fork-type piezoelectric resonator plate is one piezoelectric resonator plate used in piezoelectric resonators. A tuning fork-type piezoelectric resonator plate is a piezoelectric resonator plate shaped like a tuning fork that consists of a base portion and a pair of vibrating legs (hereinafter, referred to as leg portions) extending in one direction from the base portion, and tuning fork-type piezoelectric resonators that use tuning fork-type piezoelectric resonator plates are widely used as the clock source for clocks.
For example, with a tuning fork-type piezoelectric resonator plate described in the Patent Document 1, joining portions that join to an external portion are furthermore formed protrudingly from the other end face opposite to the end face of the base portion on which the two leg portions are formed. These joining portions that protrude from the other end face of the base portion are formed so as to branch in a T-shape along both side faces from the other end face of the base portion and extend such that respective tip portions thereof face in the same direction as the tips of the two leg portions.
With this tuning fork-type piezoelectric resonator, the main body casing is constituted by a base and a lid, and inside the main body casing the tip portions of the joining portions of the tuning fork-type piezoelectric resonator plate are electromechanically joined to the base using a conductive material, and the tuning fork-type piezoelectric resonator plate thus joined is hermetically sealed inside the main body casing. This tuning fork-type piezoelectric resonator enables vibration leakage (acoustic leaks) to be prevented.